1. Field of the Invention
The present invention relates to a roll winding device with an unwinding station and a winding station. This type of roll winding device may be utilized, e.g., in the unwinding and subsequent winding up of material web rolls. Applications for the roll winding device of the present invention may include, e.g., rewinding or cutting of rolls from an operational width of the production machine to a usable width for consumers.
2. Discussion of the Background Information
Material webs, e.g., paper or cardboard webs, are generally wound onto winding cores made of cardboard tubes for distribution after production. These winding rolls, and in particular, wide winding rolls, are generally supported by carrying rolls or backing rolls during the winding procedure because the cardboard tubes do not have the necessary rigidity and bearing capacity to avoid a bending of the roll due to the increasing roll weight.
Progress in paper production, as well as demands of consumers, e.g., printers, have led to a stark increase in the dimensions and weights of paper rolls. This increased size consequently increases the pressure with which the winding rolls rest against the carrying rolls or backing rolls during the winding procedure. As a result, imperfections in roll assembly are cause, e.g., formation of bars or crepe creases. In addition to these drawbacks, the higher roll weight on the winding location results in a higher pressure, which results in greater winding tightness and other problems. Moreover, because the weight increases with the increase of the roll diameter, winding tightness increases outwardly from the inside of the roll, which is basically undesirable. In fact, the opposite tightness progression is much more desirable, i.e., an outwardly decreasing winding tightness from the inside of the roll.
In an attempt to compensate for the influence of the roll weight, compressed air bearers, air cushions, or belt relief mechanisms have been used. However, this compensation is difficult because, e.g., roll supports with air cushions or compressed air bearers require a considerable amount of energy. This becomes immediately apparent when it is considered that the rolls to be wound will have a diameter in the range of between 1,000 and 2,100 mm and a width between 400 and 3,800 mm. Moreover, the weight of the wound rolls will generally be within a range, e.g., between 3 and 10 tons. Further, in spite of these very high masses, a high production speed should nevertheless be attained, e.g., up to 3,500 m/min.
German patent application 197 34 830 discloses that vertically arranging the axis of rotation can be used to overcome the above-noted problem. In this arrangement, at least the material web runs on a vertical plane in one area either shortly before winding onto the roll or after leaving the roll. When resting on a support or stand, the winding roll can no longer produce radial forces with its own weight.
However, when winding in this manner, i.e., winding with a vertically positioned axis of rotation, it is not very easy to access the material web at the beginning of the winding process. The broader the material web or partial web to be wound, the greater the height at which an operator must work, e.g., when fastening the partial web or material web onto the roll core. Further, due to the weight of the material web roll itself, crease formation is sometimes observed, which reduces the winding result.